The Netherlands is largely wetlands, so the country is classic habitat for the European eel (Anguilla anguilla), which was until relatively recently a common fish of the marine/brackish coastal area, found in rivers and wetlands. At high tide, half the country would be flooded were it not for the dikes and other water controls. Notably, many dikes, dams and sluices have been improved in the Netherlands during the past 100 years, to such an extent that migration of any fish became almost impossible. In 2008 the Netherlands had 4,671 pumping stations, 8,488 dams and 2,278 sluices, which given their advanced engineering, resulted in an almost complete barrier to fish migration (Fig. 4.1; Kroes et al. 2008).